After a devastating experience on the now-canceled spinoff Ravenswood, Caleb (Tyler Blackburn) makes his way back to Rosewood, Pa., in the "massive" 100th episode, which sees Alison DiLaurentis (Sasha Pieterse) returning to the halls of Rosewood High. Alison won't be the only one dealing with conflict; Blackburn says that Caleb post-Ravenswood is a completely different beast.

"The last episode of Ravenswood, Caleb seemingly defeated the pact and when he comes back to Rosewood, he's a lot darker than he was even when Ravenswood ended. You're kind of wondering, 'What's gone on?' " Blackburn tells The Hollywood Reporter. "As the episodes go on, he starts to describe everything he's been through in Ravenswood. He comes back very damaged. He's just angry — he has a big, big chip on his shoulder."

As for Caleb's return to town, Blackburn hints that while "everyone is happy to see him back, they're a little confused," wondering where he's been. "But several people step up to the plate and try to help him," he hints.

Hanna (Ashley Benson) and Caleb, at the moment, have a long road ahead in the romance-rekindling department. "They are both in a very confused, dark place, so they have that in common. Caleb's not ready to get back into a relationship. Caleb's sort of isolating himself, but they do look to each other because of what they're both dealing with, as far as how they're feeling about life and other people," he says. "They're there to support each other."

Adds Blackburn: "They both started to move on. It's a different dynamic than they've experienced before."

The 100th episode also marks Caleb's first meeting with Alison. "He only knows her based on what he's been told. He doesn't like her. He doesn't trust her," Blackburn says. "They butt heads and that's fun."

For Blackburn, coming back to the Warner Bros. backlot in Burbank, Calif., where the Pretty Little Liars films, was a welcomed homecoming.

"It felt like no time had passed and that felt very meaningful — I was home in a way. It was crazy to go film Ravenswood in New Orleans and be somewhat connected to Pretty Little Liars, but not," Blackburnsays. "I felt great coming back. I had a lot of warm welcomes. I got right back in the groove."

Even so, the actor has high hopes that the Ravenswood storyline receive some sort of finite ending. "It's deserved," Blackburn says. "The episodes do touch on Ravenswood, so we'll see if anything else happens with it."

The final minutes of the 100th episode are not to be missed, Blackburn promises. "At the end of the episode, there's a huge thing that happens that brought all of the characters together under one roof. Viewers are going to be stunned."